What is the recommended dose of omeprazole (Proton Pump Inhibitor) for adults?

Omeprazole Dosing in Adults

For most adult indications, omeprazole is dosed at 20 mg once daily, taken before meals, with specific conditions requiring 40 mg once daily or higher doses up to 360 mg daily in divided doses for pathological hypersecretory conditions. 1

Standard Dosing by Indication

Peptic Ulcer Disease

• Active duodenal ulcer: 20 mg once daily for 4 weeks (some patients may require an additional 4 weeks) 1
• Active benign gastric ulcer: 40 mg once daily for 4 to 8 weeks 1
• These doses provide more rapid and complete healing compared to H2-receptor antagonists 2, 3

Gastroesophageal Reflux Disease (GERD)

• Symptomatic GERD without erosions: 20 mg once daily for up to 4 weeks 1
• Erosive esophagitis (EE): 20 mg once daily for 4 to 8 weeks 1
  • If no response after 8 weeks, an additional 4 weeks may be given 1
  • Healing rates of approximately 80% are achieved after 4 weeks, with superior efficacy compared to ranitidine 2, 4
• Maintenance of healed EE: 20 mg once daily (controlled studies do not extend beyond 12 months) 1

Helicobacter pylori Eradication

• Triple therapy: Omeprazole 20 mg + amoxicillin 1000 mg + clarithromycin 500 mg, all taken twice daily for 10 days 1
  • If ulcer present at initiation, continue omeprazole 20 mg once daily for additional 18 days 1
• Dual therapy: Omeprazole 40 mg once daily + clarithromycin 500 mg three times daily for 14 days 1
  • If ulcer present, add 14 more days of omeprazole 20 mg once daily 1
• Higher potency PPIs may be considered for patients with inadequate response to omeprazole 5

Pathological Hypersecretory Conditions (Zollinger-Ellison Syndrome)

• Starting dose: 60 mg once daily, adjusted to individual patient needs 1
• Dosing range: Daily dosages greater than 80 mg should be administered in divided doses 1
• Maximum studied: Up to 120 mg three times daily (360 mg/day total) 1
• Treatment continues as long as clinically indicated; some patients have been treated continuously for more than 5 years 1

Dosing for Chronic Cough Due to GERD

• Standard approach: 40 mg once daily or 40 mg twice daily for 8-12 weeks 6
• Studies demonstrate significant improvement in cough symptoms compared to placebo at these doses 6

Administration Guidelines

Timing and Food

• Take before meals for optimal absorption 1
• Antacids may be used concomitantly without affecting efficacy 1

Capsule Administration

• Swallow capsules whole; do not chew 1
• For patients unable to swallow intact capsules, open and mix contents with one tablespoon of applesauce 1

Missed Doses

• Take as soon as possible unless next scheduled dose is due 1
• Do not double up doses 1

Important Dosing Considerations

Drug Interactions Affecting Dose

• When co-administered with glecaprevir/pibrentasvir for hepatitis C, do not exceed omeprazole 40 mg daily (or equivalent PPI doses), as higher doses have not been studied and may reduce glecaprevir concentrations 6
• Omeprazole inhibits cytochrome P450 and may affect metabolism of drugs like phenytoin and diazepam, though generally less than cimetidine 7, 8

Dose Escalation for Refractory Cases

• For gastritis with poor initial response, dosing may be increased to 20 mg twice daily 5
• For chronic or recurrent gastritis, long-term maintenance therapy may be necessary 5

Common Pitfalls to Avoid

• Avoid dose reduction below recommended levels, especially in primary care settings 5
• Do not prescribe doses exceeding 40 mg daily when used with glecaprevir/pibrentasvir for hepatitis C treatment 6
• Review the need for PPI therapy before prescribing, particularly when used with direct-acting antivirals 6
• Ensure clear communication about the indication for PPI therapy in correspondence with the primary care team 5

Pharmacokinetic Considerations

• Omeprazole shows concentration-dependent elimination kinetics with oral bioavailability that increases with dose and during repeated administration 7
• Despite complex pharmacokinetics, once-daily dosing of 20-40 mg provides almost continuous maximum effect due to irreversible binding to the proton pump 7, 8
• Elimination half-life is approximately 1 hour, but pharmacological effect lasts much longer due to covalent linkage with H+,K+-ATPase 8